SBRI/TR-214-1423 UC Category: 630

Evaluation of Pumps and Motors for Photovoltaic Water Pumping Systems

0. Waddif^jton

June 1982

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Printed in the United States of America Available from:

National Technical Information Service U.S. Department of Commerce

5285 Port Royal Road Springfield, VA 22161

Price: Microfiche $3.00

Printed Copy S 5.25

NOTICE

This report was prepared as an account of work sponsored by the United States Government. Neither the United States nor the United States Department of Energy, nor any of their employees, nor any of their contractors, subcontractors, or their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness or usefulness of any information, apparatus, product or process disclosed, or represents that its use would not infringe privately owned rights.

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tf2-EV 2-1423

PREFACE

This report documents work done on SERI tasks 3825.70 and 1091.50 by members of the Advanced Systems Research Branch of the Solar Electric Conversion Research Division and of the Thermal Systems and Engineering Branch of The Solar Thermal and Materials Research Division. The task extended from October 1980 through September 1981 and was supported by the Division of Photovoltaic Energy Systems, Office of Solar Applications for 3uildings of the U.S. Department of Energy.

The authors wish to thank Cecile Leboeuf, Jane IJllraan, Rick Noffstnger, and Howard Walker for technical assistance given during the project. Also, appreciation is given Co John ?. Thornton for his work in. the a-ifly stases of the project and to Charles Bishop, Chief of the Systems Development branch in which the majority of the work was accomplished.

David Haddington, Task..Leader Advanced 3vsterns Research Br.-.nch

.D«,:;.-"M \ ^ P Approved fo r

CO t-c • j V J ; ' . ^

SOLAR ENERGY RESEARCH INSTITUTE-: ^ v v C ^n . . . ;7 r- :;.,• Vy&S'

E l t o n 3uel l j , , Chief Advanced Systems Research 'Branch1 ' ';~'r-

Donald R i t c h i e , Manager S o l a r E l e c t r i c Conversion Research D i v i s i o n

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SUMMARY

Two electric, motor-driven water pumps were tested in conjunction with a photovoltaic (PV) array that provided the electrical energy to run the pumps= The purpose of the tests was to evaluate the performance of currently available, low-cost pumping systems powered by PV arrays. The performance and cost of these systems were compared with analogous data from similar, higher priced pumps and motors currently used with many PV water pumping systems.

The two pump systems considered represent production equipment available from U.S. industry and cost less than 50£ of equivalent pumps installed with PV pumoing systems in the United States and in developing countries, "low rates, pumping heads, and efficiency wece comparable in both test pumps and equiva­lent pumps. Motor performance, when the motor was directly connected to the ~V array and loaded with the pump, was examined. The conclusion drawn from t.-.is experiment is that commercially available, low-cost wateu pump systems will perform satisfactorily when powered by PV arrays.

The test facility constructed for these tests consists of a trailer housing the Instrumentation, controls and pump subsystem, and tvo solar array? that provided up to 1500 '1 power. Two battery storage subsystems provide instru­mentation power when solar energy is not available. This facility can -.o"? be used for further tests, for orientation, or to provide hands-on trai-.-.ing for persons interested in using PV-powered systems.

v

TABLE OF CONTENTS

? a S e

1.0 Background . . . . . . . . 1

2 .0 Approach 3

3.0 Exper imenta l Set Up 7

3 .1 Factlitv • • 7

jt_ ': jy'~-^ .. J ii :1 3 "•*? u 5*̂ 1 • » » • « » » • » . » • • • • • » » » • • • • • . • * • . . • • . . . » . . . . . . . . . . . . . . v

3.3 Pump Subsystem 11 3.- Measurement System 14

i.: Performance 4. 19

4.1 Laboratory Tests 21 4.2 Solar Array Tests 22

4.2.1 Solar Array Tests on ?AC0 Pump with 30-V Motor 22 4.2.2 Solar Array Tests on Crane-Demming Pump with 90-V Motor.... 27

4.3 Comparison of Punp Performance 30

5,0 Conclusions and Recommendations J7

Appendix A Motor-Solar Array Performance Requirements 39

Appendix B Equipment Li3t 41

Appendix C Computations and Conversions 43

Appendix D Data on ?ACO Pump with 30-V Motor (Laboratory Tests) ^5

Appendix Z Data on Crane Deeming Pump with 90-7 Motor

(Laboratory Tests).... 47

Appendix ? Performance Summary for PACO Pump System (Solar Tests) 49

Appendix G Performance Summary for Crane-Demming Pump

System (Solar Tests) 31 Appendix H Procedure for Design of a Water Pumping System 53

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LIST OF FIGURES

Page

Test Facility . 7

Solenergy Array 9

Low-Cost Array Support 9

Solarex Array 10

\d justabls Ariray Support. .,..., 10

Schematic of Power Subsystem 12

?AC0 Pump, Manufacturer's Data 13

Crane-Denming Pump, Manufacturer's Data 13

S'cetch 3f ''•imp Subsystan 14

Punp Subsystem 15

Control Rack 16

Performance and Efficiency, ?AC0 Pump with 30-V Motor 20

Pump Characteristics, Crane-Denming Punp with 90-V Motor 21

Performance and Efficiency, Crane-Denming Pump with 90-V motor 21

Operating Characteristics of 20-7 Motor with Solar Array 23

Insolation vs. Tine, PACO Pun? Test 24

Solar Array Power vs. Time, PACO Punp Test 24

Water Flow vs. Time, PACO Pump Test 25

Solar Array Voltage Change vs. Insolation, PACO Pump Test 25

Average Flow Rate vs. Voltage, PACO Pump Test 26

Average Flow Rate vs. Insolation, PACO Pump Test. 26

Average Pressure vs. Voltage, PACO Pump Test 27

Operating Characteristics of 90-V Motor with Solar Array 23

Average Insolation vs. Time, Crane-Denning ?unp Test 29

Ix

LIST OF FIGURES (Concluded)

Page

4-14 System Power vs. Time, Crane-Demming Pump Test 29

4-15 Average Flow Rate vs. Time, Crane-Detnming Pump Test 30

4-16 Average Array Voltage vs. Insolation, Crane-Demraing Pump Test 31

4-17 Average Flow Rate vs. Solar Array Voltage, Crane-Demming

Pump Test 31

4-18 Average Flow Rate vs. Insolation, Crane-Damming Pump Test 32

4-19 Average Pressure vs. Solar Array Voltage, Crane-Demming Pump Test... 32

4-20 Average Voltage and Temperature vs. Insolation .5... 33

4-21 Pump Performance Comparison 33

LIST OF TABLES

Page

3-1 Characteristics of Solar Arrays 8

3-2 Batteries Characteristics 11

3-3 Characteristics of Motor-Pump Subsystem 12

3-4 System Measurements 17

4-1 Comparison of Pump Characteristics 25

x

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SECTION 1.0

BACKGROUND

Water is a prime necessity for human existence, and as Che standard of living in developing countries improves, the demand for water increases. Furthermore with the lifestyle change from nomadic hunters to ranchers who raise their food or food for domestic animals, the water requirement has become even greater. Windmills have pumped water in coastal regions and other areas with reliable and consistent winds for centuries. If adequate winds are not avail­able, farmers can often grow only one meager crop per year during the rainy season. Yet with an adequate water supply, this farmer :-ould raise four crops. Photovoltaic (?V) energy conversion provi.i .-.; energy :;r •.i-;.- •v.-pir. r and other uses in areas where there is consistent solar insolation but where wind energy is not adequate. Several companies have developed pumps that operate from ?" arrays, but they ar; expensive and have technical vimitations.

Guinard of Prance has developed a pump that uses a Jc motor on the surface to drive a pump at the bottom of a well by means of a long shaft connecting the motor to the pump. Tie shaft requires bearings at 1-m intervals, which adds to the friction o.lr̂ ?.d̂ oresent ~rom the water on the "roving sha^t • If sand gets in the water, it also gets into the bearings and causes '-ear.

Tri Solar Corporation of Bedford, Mass., makes a small, submersible water puno that uses a brushless dc motor directly connected to the pump and submerged with it. This pump and motor are necessarily limited to about 1/3 horsepower because the transistors used for commutation of the brushless motor are cur­rently limited in both voltage and currant-carrying capability.

In 1980, the cost of both of these pumps was equivalent to the cost of the solar array required to drive them. A major Department of Znergy-Soiar Energy Research Institute (DOE-SERI) effort was expended to try to decrease the cost of ?V arrays. Therefore, this task was initiated to decrease the cost of the pump and motor while increasing simplicity and reliability. The objective of this task was to evaluate pumps and motors together with batteries that could be used with a PV-powered water pumping system. This task was designed to evaluate two pump-motor systems that were less expensive than those systems tested in foreign countries. Another objective of the task was to compare low-cost, electrical vehicle batteries to batteries designed specifically for use with PV systems. The final objective was to provide SERI with a photovoltaic energy source and pump testing capability that could serve as a demonstration for visitors, a systems research facility, and also as a training center for those who wish to learn about water pumping systems.

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SECTION 2.0

APPROACH

Many inputs and requirements are needed to design a ?7-watar pumping systam. The major system design criteria included economy, reliability, maintain­ability, and safety.

Economy: The system should be of the lowest cost consistent with meeting other requirements.

Reliability: The system should have the minimum number of components, be of the least complexity, and must have beer* proven through years of usage.

Maintainability: The system should require little or no iaintenar.ee and any required must be capable of accomplishment with a minimum of technical knowledge and a minimum of tools.

Safety: The system must offer the minimum hazard to personnel not familiar with operating electrical rotating machinery.

To meet these design criteria, batteries were no1: considered as i oart of the water pumping system. '"atar can be stored much more reliably and economical!/ than energy needed to pump water. '-'atar storage can he 100:*' efficient if evaporation is prevented, whereas energy stored in batteries is only 35" to 90% efficient. A nominal, 23-7 system was originally chosen because Lt did not present an electrical shock hazard to inexperienced personnel. However, it appears that developing countries have negligible problems adapting to the higher voltage of the European 220-V standard. To ensure low cost, reliabil­ity, and minimal maintenance, standard U.S. pumps and motors with an estab­lished record of dependability were needed. Although pumps were available, it was difficult to procure reliable motors. While the brushless, dc motor offered potential reliability and maintainability, it was still in the devel­opmental stage and was not available larger than i'3 hp. Finally a brush-type, permanent magnet motor was selected, because it started with low current and had lower losses than the mora conventional shunt-wound motor. It was available from the Motor Division of Honeywell.

A number of pump types were evaluated for the experiment. It was desirable to use a pump that could be operated over a wide range of well depths. The jet pump, often used for residential water systems in rural areas, was first con­sidered but was rejected due to its inefficiency. This pump moves three to four volumes of water at high velocity around a loop from the top of the well to the bottom and back again for each volume it pumps. The old standby piston pump, operated by hand or wind for many years, was next considered. This pump is the only one to consider for extremely deep wells (of the order of hundreds of metres) but is disadvantageous for use with a solar power system because the load is periodic between the up and the down stroke. This can be balanced by using batteries, which incur an additional expense and maintenance prob­lem. Centrifugal pumps offered the highest efficiency and also offered the optimum operation with a solar-powered system because they could be directly connected to the motor shaft.

3

SE?! »

A shallow well centrifugal pump was chosen for the experiment because it met the system design standards and could be driven by a surface-mounted motor. The difference in depth between a shallow and a deep well is about 7 m, depending on the altitude above mean sea level. A shallow well can have the punp on the surface and can pump water from any level down to about 7 m below the surface. If the water level is lower than 7 ra, the punp must be put into the well and is usually installed below the water level so that it does not have to be primed. (A pump located above the water surface must be primed. That is, the pump and the pipe from the pump to the water in the well must be filled with water before starting the punp.)

The solar array for this experiment was planned to use a single crystal sili­con solar cell commercially available in the United States. The array was initially limited to 1 kW power because of cost limitations within the task. To achieve the highest system efficiency, the motor with pump load had to be matched to the array so that the motor would operate at full speed and rated torque at the same voltage and current that defined the ̂ maximum power point of the array over foreseeable temperature and insolation values. Tne array also needed sufficient energy to start the motor as early in the day as possible. The array characteristics were plotted and sent to motor manufac­turers to determine which motor most closely matched the array when directly connected with no battery or power conditioning. Appendix A explains the motor-array performance requirements. After motor and punp loads were deter­mined and the array was sized, a second solar array was added to provide housekeeping power so that the complete system could operate in an isolated, stand-alone node.

Pump requirements were met by soliciting information about standard punps from various pump manufacturers. Most U.S. manufacturers design pumps at speeds that are consistent with induction motors driven from 60-Hz mains. .Only a few manufacturers had pump data for speeds other than 1750 and 3500 rpm. The available performance curves were evaluated to determine the pump with aaximum efficiency that conformed to the power and rpm outputs expected from the motor and that provided the largest flow rate at the desired head. The step-by-step approach used to determine optimum pump motor combinations is included in Appendix H.

It was the intention of this experiment to build an operational, "stand alone" test facility. When all of the components necessary for the facility were chosen, they included batteries to run the instrumentation during periods of cloud cover and during sunrise and sunset periods. These batteries were also to be evaluated during the battery tests of the project. Where choice of instrumentation was available, instruments powered by 28-V dc motors were selected.

Batteries for the experiment required daily deep discharge at low currents on the order of C/10, where C is the battery capacity in ampere hours. The desire was to evaluate batteries that were designed for daily charge and deep discharge in industrial applications, and to compare these batteries with the C&D battery used by NASA-Lewis and others in several PV applications. Bat­teries were selected by contacting numerous battery manufacturers and com­paring battery specifications and test data to find an appropriate battery for a PV array-powered system requiring daily deep discharge and recharge. Fac­tors that were considered other than electrical performance included

SE?I m

maintenance, requirement for distilled water, and the possibilities of replacement or substitution if used in a developing country. Consideration was given only to lead-acid batteries; although nickel-cadmium batteries have excellent cycle lives and are cost effective, they have long procurement lead time, replacement difficulties, and the potential hazards associated vith cadmium.

D

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"1

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SECTION 3.0

EXPERIMENTAL SETUP

3.1 FACILITY

It was Intended that this experiment be installed on the SERI permanent test facility. Unfortunately negotiations for the site continued for over a year, and when permission could not be obtained by 1 June of 1981, it was decided to install the experiment on the interim test site. A trailer had been obtained and was already stored on the interim test site as was the small prefabricated building intended for use as a well-house to hold the pump. An area had been reserved in proximity to the trailer to mount solar arrays in Che event the use of the interim test site became necessary. The trailer had been designed originally as a mobile home, and adaptation to the experiment resulted in the kitchen and living room becoming a workshop. The bathroom became a battery room, one bedroom became the pump room, and the second bedroom became the control center. Figure 3-1 is a photograph of the facility.

Figure 3-1. Test Facility

7

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3.2 POWER SUBSYSTEM

The power subsystem consisted of the solar arrays, the batteries, and the associated wiring and interconnections. The solar array needed to operate the pump was obtained from Solenergy. The other array, that provided power for the instrumentation system and powered the data system was procured from Solarex. Table 3-1 lists the characteristics of the two arrays.

The Solenergy array was mounted on a support formed by two horizontal wooden poles attached to vertical posts set into the ground. This construction was not only economical but was a representative support that could be built in a developing country with local labor and native materials. Figures 3-2 and 3-3 show the array and its mounting. The spacing between panels decreases wind loading.

The Solarex array was mounted on an adjustable Unistrut framework capable of being adjusted in elevation to achieve optimum acceptance of solar radiation at different times of the year. This framework was also supported on wooden posts set into the ground. Figures 3-4 and 3-5 show the Solarex array and its support structure.

A dc battery was procured that consisted of 12 cells in two separate battery cases from C&D Corporation. This reference battery Is representative of those generally used for ?V operations. A second battery, the "George" battery, was obtained from 'Gould; it was designed to operate electric fork lifts. Table 3-2 lists characteristics of the two batteries.

Table 3-1. Characteristics of Solar Arrays

Solenergy Solarex

Cell size and type 10-c^i diam. single crystal

Panel size 78.1 cm x 121.3 cm

Panel area 0.947 m"

Cell area/panel 0.613 m

Number of panels 12

Number of celis/panea 78

Total area of array 11.3 m"

Voltage at maximum powera 31.5 V

Average peak powera/panel 70 W

Average peak efficiency 11.4%

Total powera 340 W

19S0 cost S9313

1980 S/W S11.09/W

3ased on solar trradiance of 1000 U/m and panel temperature of 23°'

9, .5

63

0

cm*" poly cry .5 cm x 120

0.762 m 2

0.650 m 2

10

72 - "> 2 /. o2 m

31 V

62 W

9.5?:

620 '.;

310,044

S16.20/W

•stal

cm

Q

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: \ M » W

Figure 3-2. Solenergy Array

Figure 3 -3 . Low-Cost Array Support

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Figure 3-4. Solarex Array

Figure 3-5. Adjustable Array Support

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Table 3-2. Battery Characteristics

C&D GQP75-5 Gould "George"

Cycle life3 1500-1800 1000

Ampere-hour 166 180

Plates/cell 5 13

"umber of cells/case 6 3

Case dimension LWH 42.5, 16.8, 57.5 cm 26, 13, 20.5 cm

Case weight LOO kg 34 kg

Number of cases 2 4

Total weight 200 kg 136.4 kg

Cost 31403 S5o0

aCycle life is defined as the number of discharge (to 30" of capacity) and recharge cycles that can be accomplished before the battery will no longer accept and hold a charge equivalent to o0% of the original.

Figure 3-5 illustrates the schematic of the power system interconnection. The solar arrays were paralleled with diode isolation in a junction box on the back of the array support. Additionally the Solarex array was connected to a dc bus with five separate relay contacts so that segments of the array could be remotely connected or disconnected in five groups for battery charge control. Power leads were connected to a patch panel on the control rack where negative leads were connected through shunts to a ground bus for measur­ing current, and positive leads were connected to patch terminals. The bat­teries, the oump motor, and the instrument power inverter were also connected to this patch panel so that multiple connections and changes could be made easily. Provisions were made so that the Solenergy array could be reconnected easily for 60, 90, or 120 V.

The inverter chosen to power the instrumentation requiring ac power was made by Advanced Conversion Devices Company. The unit is rated at 1 kVA, 120 V, 60 Hz, and is designed to operate between 13 and 32 V dc. The output is a nominal sine wave with not more than 5™ distortion.

3.3 PUMP SUBSYSTEM

The system used two pump-motor combinations. The first motor was chosen to work with the nominal, 23-V system for safety precautions; the second motor operated at 90 V since this was a U.S. standard for variable speed motors. Table 3-3 specifies the characteristics of these subsystems. Figures 3-7 and 3-8 present the performance characteristics of the two pumps.

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£~~T x

Solar Array 1

i i. A

Solar Array 2

t s ( ^ <*7^Amps

dc Paten Panel

o o-

^

r Battery 1 Motor to Run Pump

• Additional • dc Loads

I — aatterv Additional Returns

} \ n , di J_ z—-Current i ~ Shunts

Inverter

F i g u r e 3 - 6 . Schemat ic of Power Subsystem

Table

Mo t: r Manufacturer Type Voltage Current hD rpm

Punn Manufacturer Type Stage Inlet pipe s Outlet pipe 3earings Per romance

3-3.

iza size

Characteristics of >8ot

Subsystem 1

Hone well 3A3S37-3254-483 30 V 24 A O.S 2600

Pacific Pumo Co. L-1505.5 Single 1 1/2" MPT 1 1/4" MPT Sealed ball See Fig. 3-7

or—Pump

(P-*.C0)

Subsystems

Subsystem 2

Ho ne '.̂ ve 11 3R53 TE7C-56BC 90 V

9.5 A 1 1750

Crane-Denning 3914-131-OU-0O2 Single

T NPT 1 1/2" MPT Sealed ball See Fig. 3-3

3 ! # TR-L423

X

2 o

120

110 100

90 80

70 60 50 40 30 20 10 0

I i

-3600

-3400

"3200

3000

^2800,

2600 240Q j

tr"2200 -2000 ^J866' _i4oq_ -1000

1 I.

; 5-7/64" 1 a\° vJ 1

C J •*-

T*"^

^ " ^ ! ? : > \ > ^" • •^C

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Diam. Imp. T"' I 1 1 ! 1

PACO Model 1250-5 o\° Curve 13135 ~

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Date 9/65 -»

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K)vV

1 1 1 1 1

_ 3

15 30 45 60 75

U.S. gai/min

90

F i g u r e 3 - 7 . PACO Pump, M a n u f a c t u r e r ' s Data

6"-Oiam. Impeller for all rpm

• 3

0}

X

60 100 120 U.S. gal/min

Source: Deming Division. Crane Co. "Curves show oerrorTiance with liquid naving scecific gravity—1.0 viscosity—30 SSU

F i g u r e 3 - 8 . Crane-Demming Pump, Manufac tu re r ' s Data

13

5=33 #

The pumps were individually set up as shown in Figs. 3-0 and 3-10. Figure 3-10 also shows the torque sensor mounted between the pump and the motor. In this photograph, water is pumped from a tank directly under the purap and returned to that same tank. The white tank on the right was used as a measured volume to calibrate the flowmeter.

3.4 MEASUREMENT SUBSYSTEM

Figure 3-11 shows the control rack and the readout portion of the measurement subsystem. Insolation is measured with an Eppley Pyranometer mounted at the same azimuth and elevation angle as the fixed Solenergy array and is supported above the trailer on a Dole that also hold? the wind sensors. A. digital volt

meter : ve :mo oane-L rocuces tme r.^H-an. cut 7h ' _C-'1. *..i d a1 *

Tie second panel produces wind soeed and wind direction data. Tie wind censor is counted on a pole beside the trailer ac ? n above the ground, "ir.d data are also recorded by the data system so that the effects of wind cooling of the arravs can be determined.

- 1 , i - - ? oana±. provider • »•» sua. .cou; • . . H

•••oitases are measured a t e i t n e r source i r rack in tw i s t ed c-air s h i e l d e d c a b l e s . This set-: mower laa J . r e s i s t a n c e in the measurements . C;

" 'mad and i re brmu^ht to the c o n t r o l n e l i m i n a t e s '.'•;! ta-^e dr:>n from

.1 measured w "0—?.'•' shunts and a 15-uV meter calibrated to •read the 5;,> •?.'.' full scale which negates the effect of contact resistance in the selector switch.

£ 2

Flow Meter

<f> ©§©

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Volt Ameter Meter

U -

Figure 3-9. Sketch of Pump Subsystem

14

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Figure 3-10. Pump Subsystem

The fourth panel contains the Auto Data 10 system. This instrument .-scans 100 channels at preset rates in a fraction of a second. The basic unit measures voltages but has internal, programmable computation that -mathe­matically manipulates data to provide meaningful readouts (e.g., a thermo­couple can be read out in either degrees Fahrenheit or Celsius). The instrument can record flow rate in either gal/mln or L/s. It can also multiply voltage and current Co give watts that can then be integrated to watt-hoars or averaged over a period of time. The data system operates by remote control from a terminal, and a data cassette records data for subsequent analysis.

Instruments in the fifth panel (directly above the power patch panel) are used for pump control and monitoring. One meter presents pump pressure as a dif­ferential pressure between the outlet of the pump and the pressure in the feed pipe at water level in the storage tank. This pressure is converted to an analog voltage for meter indication on both this panel and a panel by the pump and also for recording. Flow is measured with a turbine-type flowmeter that modulates an RF carrier to provide a rotation rate that can be detected, counted, and presented digitally as shown in the local pump panel, Fig. 3-10, as well as provide an analog voltage for recording and remote readout on the control rack.

Table 3-4 lists measurements taken from the system. Appendix S lists che instrumentation of the system.

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Figure 3-11. Control Sack

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Table 3-4„ System Measurements

Measurement Data

System Channel

100 130 162

131 135 101 150

111-112

132 136 102 162

113-114

133 10 5 163 113

134 106 154 119

135 1«7 103 107 133 108 134 167 163 155

__ 115 115

110 117

Visual Presentation at Control

MV — -—

TT

A — —

\r

•• ' — A — —

T*

A — —

TT

A — —

Va

— Aa

a ?s-?

gpm — —

a a — —

— —

Pyranometer (W/m~) Pyranoraeter, 15-min average (W/m^) Pyranometer (Wh/m )

Solar Array 1 Voltage Solar -Array 1 15-nin average voltage Solar Array 1 Current Solar .Array 1 Watt-hours Solar Array 1 Temperature

Solar .Array 2 Voltage Solar Array 2 15-min average voltage Solar Array 2 Current Solar Array 2 Watt-hours Solar .Array 2 Temperature

Battery 1 Voltage 3attery 1 Current Battery 1 Ampere-hours Battery 1 Temperature

3attery 2 Voltage Battery 2 Current Battery 2 Ampere-hours Battery 2 Temperature

Pumo Voltage Pump 15-min average voltage Pump Current Punp Pressure Pump 15-rain average pressure Pump Plow rate Pump 15-min average flow rata Pump Total volume (gal) Pump Watts output Pump Motor watt-hours Pump rpm Pump Motor torque Pump Motor temperature Pump 3earing temperature

Ambient Temperature at arrays .Ambient Temperature at batteries

Also visually presented at pump location.

S=?! T } _ T /, n "̂

Table 3-4. Measurements (Concluded)

Measurement Data System channel

136 104 141 142

109 137

Visual Presentation at Control

" A ;: A

muh -ia?

Inverter dc voltage Inverter dc current Inverter ac '/oltage Inverter ac current

Wind velocity (m/s) "ind direction (rad)

Special instrumentation Counter to provide divisor for averaging Rtf-ret to reset counter to ser-Stabilized bus voltage 20-s

time constant to prevent hunting of array switchins relays

30

Array switching relay 29.4 V Array switching relay 29.6 7 Array switching relay 29.3 7 Array switching relay 30.0 7 Array switching relay 30.2 V

1 "">

13i

Also visually presented at pump location.

IS

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SECTION 4.0

PERFORMANCE

Tests were performed on both pump subs'/stems in Che laboratory and in the field using Che solar arrays for power.

4.1 LABORATORY TESTS

The pumps were individually sec up as shown in the photograph (Fig. 3-10) and run from ?. dc power supply so Chac the input power could he controlled. This il*-! rr ;vi!ed an opportunity to calibrate the pressure and flow rat.? sensors. Pressure was calibrated by parallel connection of a reference gauge ani comparison of the reading. Flow rate was calibrated by diverting the flow into a calibrated vessel and measuring the time required to flow a given vol un e • . *

•?atj. "ron the 30-7 pump subsystem that indicated potential ?V performance from manually adjusted voltages were:

» the no tor would start turning at 4 V and 6 A;

• a:tif starting, the no cor would continue to run down c; 2 V; and

• when the power was increased, the pump would start pumping at 350 rpm, which corresponded to 10 7 and 6 A.

ror the main test, the pump was run by Che motor connected to the power sup­ply. The power supply was adjusted to 30 V, and the system turned on so that water flowed. The throttling valve was then adjusted to vary the effective head on the pump and data were recorded. The Cesc was repeated at 24 V.

:!oc-;r data were: Voltage Current rpm Torque

Pump data were: Pressure Flow rata

Computations were then made as follows:

a. Motor input watts 3 voles • amperes b. Motor output watts = T • S/X

Metric English where T = torque M-m in-lb

S = speed rpm rpm K* =• 9.349 JI-a/W-rad 34.43 in-lb/W-rad

Coefficients are derived in Anoendix Z.

s=?i TR-

Pump output watts

where pressure flow

c*

Metric •cPa L/s 1 W/3 kPa

English lb/in2

?p™ 0.439 K/svin/in-

1b • sal

d. Motor efficiency = motor output * 100/motor input e. Pump effiency = pump output •< 100/motor output.

From these data (which are included in Appendix 0), the average motor efficiency was 75.8" when operated at 30 V, and 79.2" when operated at 24 7.

: ;?ir: 4-1 snows numo performance urina u -̂ o v

efficiency was 45.5?! which, when multiplied by a motor efficiency of 75.4", gives a subsystem efficiency of 34%.

:iiiVir tests •••/era performed on the Crane-Damming pump ooerit»d by the 90-7 motor. Tie pump operated at different voltages and the pressure was adjusted through a number of steps at each voltage. Appendix £ gives the data obtained -:*om these tests. This pump will start turning at 14.5 7 and 1.5 A, and will iZ3.cz pumoing at 36 7 and 2.2 A, which corresponds to 650 rpm. Figure 4-2 illustrates the effect that changes in input voltage with no flow restriction have on rarious parameters, while Fig. 4-3 presents the change in efficiency and oressura as the flow rata varies.

175

150 -40-1

10-«

c a o

uj

30-

20-

_125

CL

~100 a ^ 75

I 75

50*-

25

0

10 Pump Flow Rate (gal/min) 15 20 25 30

T 35 40

0.5 1.0 1.5 Flow Rate (Us)

45

Figure 4 - 1 . Performance and Efficiency, PACO P u n p with 30-7 Motor

SS33 » TR-li23

a.

V) tr

1.1 10CH 2000 T 200

75- 1500- 150

50-

•?«-<

1000-

500-

0-I 0-

100

* ^

& = Pressure

S = rpm

(•) = Flow Rate

30 90 100 Volts on Motor

110 120

Figure 4-2. Pump C h a r a c t e r i s t i c s , Crane-Demming Pump with 90-7 Motor

i50r

50-i 1251-

40

30-o c

I 20-

10-

0.5 1.0 1.5 2.0 2.5 3.G Flow Rate (Us)

Figure 4 -3 . Performance and Eff ic iency, Crane-Demming Pump with 90-7 Motor

jjam ana a * j ,£* TR-1423

4.2 SOLAR ARRAY TZSTS

The two punp motor subsystems were each set up to operate from the Solenergy array. The punp was connected to the array and started as soon as the avail­able Insolation provided sufficient energy. A relay connected to the second array turned on the inverter to power the data system as soon as the Solarex array reached 24 V. The data system then ran on the combined battery-solar power until darkness caused the relay to drop out.

4.2-1 Solar Array Test3 on PACO Pump with 30-7 Motor

Figure 4-4 plots the performance of the subsystem in a group of current-voltage (I-V) curves of the solar array. These results may be comoared v.ith the typical specification for the motor performance shown in Fig. A-l.

."•ir-*-.-. v.-i -TOIt"1? ir.crs.-sa with insolation along line ?. representing the ef tacti ."2 resistance of the armature and brushes. At point T 'there is suf­ficient torque to start the motor turning. Generation of back SMF rapidly incr̂ a.5.3 5 the --oltaga on the solar array and the motor with little increase in -':>?. vor-ent. \t ^oint ^ the pump starts pumping and increases directly with i r. ? •":. •>. r i - -.. rr-om the ourva Lt is apparent that the motor would have matched the array mora Efficiently if it had operated at its 30-V rating instead of at

Fir.iras 4-5, i-6, and 4-7 show the dat3 that resulted after operating the pump for a complete day. These figures show the variation of the insolation, the power generated by the array, and the flow rate of the ourap with respect to the time of day. Figure 4-3 shows the change in solar array voltage with respect to insolation. This voltage was about 1 V above the motor because of resistance losses and one diode drop. The double curve resulted because the temperature jf tha array was warmer in the afternoon so that the voltage was lower -or the same value o? insolation. This effect is discussed in detail in .-,ec. -.:.. In conjunction with tests on the Crane-Denraing outnp when temperaturas ./era recorded.

The sharp rise in the voltage curve at 350 rV/m~-insolation was caused by the hack EM? of the motor. Below this insolation the motor does not rotate and the voltage drop was caused by resistance of the armature and brushes. After the motor started, the back EMF allowed the voltage across the array to increase (Figure 4-4 also showed this relationship). Figure 4-9 presents 15-min average flow rate change with voltage on the solar array; the pump started pumping at 7 to 3 V. This flow rate is also plotted against inso­lation in Fig. 4-10 and again shows the point that pumping started.

The pressure at the pump outlet was referenced to the pressure in the pipe at the water level in the simulated well tank. When the pump is stopped or run­ning below pumping speed, the head of water between the pump and the water level in the tank represents a positive pressure on the reference side of the sensor against atmospheric pressure on the normal pressure side. This is the negative pressure shown in Fig. 4-11. The pressure goes through zero after the pump starts pumping at about 10 V, and creates enough flow to attain atmospheric pressure in the pioe at water level. As flow increases, the pressure increases.

T R _ l i 2 3

SKI

Solar Intensity (mW/cm2) , . 1 2 0 — • «

Locus of Maximum Power at

56 'C LOCUS of

Maximum Power at

28 "C

Locus of Maximum Power at

0°C

20 24 28

Voitage (V)

Figure 4-4. Operating c h a r a c t e r i s t i c s of 30-V Motor with Solar Array

TR-L423

1200

' ime ihi

_ 3

F i g u r e 4 - 5 . I n s o l a t i o a v s . Time, ?AC0 Pump Tes t

700

12 14 Time (h)

16

- 3

Figure 4-6. Solar Array Power vs. Time, PACO Pump Test

24

5=33 # TR-U2:

Time (n)

Figure 4-7. Watar Flow vs. Time, PACO Pump Test

200 400 600 300 Average Insolation (W/m2)

1000 1200

Figure 4-8. Solar Array Voltage Change vs. Insolation, PACO Pump Test

2=;

;=?! # TT5 _1 i t 1

J.U

2.5

Ra

te

(Us)

o

ige

Flo

w

en

5 1.0 > <

0.5

0.0

- I ' '" '

-

-

!

I ' I ' I '

S>' '

1

I

1 ! 1 1 1 >

1 1 | 1

__

^ > - r ~ - " • —

-

i

J 4

1 : ! ! 1 200 400 600 300

Average Insolation •W7m2'j -000 :200

F i g u r e 4 - 9 . Average Flow Rata v s . V o l t a g e , PACO Pump Tes t

15 SA1 Voltage

30

Figure 4-10. Average Flow Rata vs. Insolation, PACO Pump Test

4.0

SS3! TR-1423

65

(a QL

45

<n

05 (0

> <

25

-15 J. 10 15

SA1 Vo'tage

25 30

Figure 4-11. Average Pressure vs. Voltage, PACO Pump Test

4.2.2. Solar Array Tests on Crane-Dennnin(> Pump with 90-7 Motor

Starting tests similar to those made on the ?A'~n s-^Cii wsri perfumed on :he Crane-Deiaming pump-motor system. Figure 4 —12 Lllustr-.tas the char-act eristic curves of the Solenergy array reconnected to generate Q0 V, overlaid with ;he operating line of the motor driving the pump. As insolation increases to 12.5 mW/cm , the current increases toward point R, which represents che resistance of the armature and brushes. tfhen the current reached 1.2 A, the 0.23-N-m starting torque is achieved, and che motor starts. Rotation generates a back Z?fF which quickly increases the array voltage. Pump speed, voltage, and current all rise with increased insolation to point ? where the pump starts moving water. As insolation increases, the operating curve passes through the maximum power point of the array that promotes maximum efficiency of the arrav-motor combination.

Data on the Crane-Demming pump were taken on numerous days, all with some cloud cover. Figure 4-13 shows the time variance of insolation on 9 September 1981; Fig- 4-14 shows the system power delivered by the solar array to the motor with respect to time. The flow rate created by the pumo with this insolation and power is illustrated in Fig. 4-15. The average vol­tage of the solar array is about 1 volt above the pump voltage because of the isolating diode and loss in the leads. The variance of 15 nin averages of

S=3J # TR-1^23

1 - T — T Solar Intensity

(rnW/cm*

Locus of Maximum Power at

56 °C Locus of

Maximum Power at

28 °C Locus of

Maximum Power at "1

O'C

Figure 4-12. Operating Characteristics of 90-V Motor with Solar Array

28

SBx] w T R - U 2 3

1200

10 12 U 16 13 Time (h)

Average I n s o l a t i o a V3. Time, Crane-Desnuing Pump Tes t

F i g u r e 4 - 1 4 . System Power v s . Time, Craae-Denmiag Pump T e s t

29

73-1423

3 10 12 14 16 Time (h)

Figure 4-15. Average Flow Rate v s . Tine, Crane-Deuming ?ump Test

:.iis voltage with insolation is shown in Fig. 4-16, voltage occurred at 100 W/m" solar irradiance because o;

A fast increase . - an increase in b

T.Tc caused by speed up of the motor (Fig. 4-12). The flow of water started about 40 V and increased linearly with voltage (Fig. 4-17). The indica flow rata, below the voltage required to create pumping speed, is caused system noise in the radio frequency flow rate sensor. This is demonstra nore clearly in Fig. 4-13 where flow rate is plotted against insolation, variance of pressure with respect to solar array voltage is identified

4-L" which shows an apparent negative pressure at the start explained for the ?AC0 oumn.

m ac .c at

ted by ted The in

was

Figure 4-20 shows a voltage-insolation curve from data collected on a day when there was little wind and few clouds. The temperature of the array is plotted on the same sheet and explains how two different voltages are obtained for the same value of insolation. 'Then the array is cold, the voltage is higher. This effect was demonstrated on the characteristic curves of the arrav in Fig. 4-12 and for the PAC0 pump in Fig. 4-8.

4.3 COMPARISON OF POMP PERFORMANCE

Because the data were collected in the autumn, rain clouds and sometimes rain were frequently present each afternoon. This condition prevented a realistic comparison of pump systems on a total volume basis. Since total power and total volume pumped varied with daily insolation, data from one day to the next were compared on a volume/kWh basis. These results are given in Fig. 4-21; the first three bars represent the ?AC0 pump and the last four bars represent the Crane-Denning Pump. The variations are primarily due to

30

!~1 # 4? •>

measurements of insolation below pumping speed, which contributed to input but not to output.

Sir William Harcrow and partners* recently completed a study on water pumping for the "orId 3ank. Table 4-1 is an excerpt from that report with four additional lines showing similar data from the two SERI-testad punip systems. One set of data represents tests and another set represents manufacturers' sales data. From these data it can be seen that the SERI pumps had a slightly larger flow rate than the majority of those tested by Harcrow et al., and were lower in efficiency at low head but higher in efficiency at high head. Tyoi-cally, the larger the centrifugal pumps, the more efficient they can be made. Clearances represent a smaller percentage of cross sectional area and more care ^oes into the design because of increased cost. Special purpose oumos :ar..2;.•=:.iiv ha'/e higher erficienc" tbaa commercial oums but t'-.eir cost L-also -\<xcr. ;nar.

100 r 3 0 ^

0)

.•o

•̂ o > < in

50

0̂

-L 200 400 600 300

Average Insolation (W/m2) 1000 1200

Figure 4-16. Average Array Voltage vs. Insolation, Crane-Demming Pump Test

*Sir William Harcrow and partners, in association with the Intermediate Technology Development Group Ltd. 1981 (July). Small-Scale Solar-Powered Irrigation damping Systems": Phase 1. CTTDP Project GLOL78/004 London.

5=*! m TH-1423

SA1 Voltage

F i g u r e 4 - 1 7 . Average Flow 3a t a v s . S o l a r Arra7 V o l t a g e , Crane-Denming Pump Tes t

200 400 600 800 Average Insolation (W/m2)

1000 12C0

F i g u r e 4 - 1 8 . Average Flow Rate v s . I n s o l a t i o n , Crane-Denming Pump Tes t

32

si?! m TR-1423

75 —

CQ 5 5 a,

w 3 W U> CD

£ 35

a > <

15

= f 20 ao 60

SAl Voltage

F i g u r e 4 - 1 9 . Average P r e s s u r e v s . So la r Array Volcage , Crane—Denmiag Pump Tes t

100

r 80

03

'-<u

"3 C S3 CJ

a (Tl ™»

o > T -

< CO

fin

40

20

-

—

~

_

-

-^rf"***

- ^ 1

1 '

Increasing

Voitage

'l l

i ' 1 ' 1 ' 1 '

!nsciatic? ^S^S**^ ^/^\>y^ Decreasing Insolation

^ y \ y ^

Ss^ ~~

Decreasing Insolation . v»_

^ ^ * * r ^ Increasing Insolation ^ ^ ^ " ^ —

Temperature

1 , 1 . 1 . 1 , IQQ ^00 600 800 1000

Average Insolation (W/m2) 12C0

Figure 4-20. Average Voltage and Temperature vs. Insolation

33

5=*! TR-1423

16

15

1 14

13

OL

Daily System Performance

PACO ?!jrr,o

Crane Demming P'JfTID

F i g u r e 4 - 2 1 . Pimp Performance Comparison

5E?I TR-1423

S u p p l i e r

Table 4 - 1 . Comparison of Pump C h a r a c t e r i s t i c s

P'jrap Typ-Sp<?eH

3 a n v e

( c p » )

S t a r t I n » Torque F.f f1ctencv

IX)

Sp*Od cr BF.P^

Mend For HEP4

(m)

ARCO S o l a r S t a - R l t e C e n t r t f u g a l 3250 J to

1/3 hp 200O

1 . 0 9 4ft : r5o

"low For f>F.p-*

! . 3

s o i r -Prl.mp

Rrlau Orlau Cencrt f ' iRnl 225n 1.25 MCV-40-1 to

150O

•>3f l n l . r . s

ITC Solar C o r p o r a t i o n

Omer* Segfd

Phocowatt

* o t h 107

E m * Ml so

i V e c r u e . t

%35

R e g e n e r a t i v e

C » o t r I f t iga !

" > ; r , t r ' f non !

1 7 3 0

t o inn

2270 to

i i n o

1.39

no 'U t - i

V ' I

Pompes Culnarrl Alr-1 *<S son/ l2

>')Ur . ^ ! e c t r t ; t ^ c e r n o c l n n . i l

"Ent Tes t '

3ERI Test

PM:O d

to 2 : iO

O o H v l n T e n c - t f i i M l i f l n n

" a n o

P*C.r) " e n t - l F u u a l 1 2 V ) - ;

J f .70 r o °-,n

Cr.nne- Contr Ifi isa I De mining

2130 to

150

PACO " e i t r l f ' m a l "''10 no tac» 1 2 5 ° - * m

; *r-o

; ^ ( i r ^

C r a n e - C e n t r i f u g a l P A W . 1 nq

2"nr> no -U.-.i

to lino

HEP • b*»c efficiency point

^ptlnura MeaH exceeds ran^e .*o*/nreH sy tests so .fzntfleant Iv hlsher »f f 1r i.»nc t«« -iav ^ «o«c|Ki..

r'?vldcnce of pump damage which .nay account for low efficiency

Manufacturer data pump only

35

Sa n W ] ;>SH-

36

5=31 $

SECTION 5.0

CONCLUSIONS AND RECOMMENDATIONS

The experiment showed thac commercial pumps and motors chat are available off-the-shelf as standard equipment from reputable manufacturers can pump water with reasonable efficiency. The standard units can be matched Co a solar array to effectively use photovoltaic energy. The pump systems are self-starting with adequate insolation and do not need to be supplemented with maximum power trackers or batteries. As the cost of solar arrays decreases because of SEXI/DOE research and development and because of mass production, the portion of the system cost represented by the pump and motor will effec­tively increase. Use of low cost units such as those tested vill then nata-rially decrease the overall system cosC, and the simplicity and reliability of Che systems will increase life expectancy.

The most important consideration in system .r.esi?n is the :a::i ;-;:w;r the pump mocor and Che solar array; Chat is, Che operating point of the no cor under load must correspond with Che loci of maximum power points on "he array over the majority of the pumping speed range. The second most important factor is selection of Che pump Co watch the >:ond I • ions of variable soeo-.i, needed head, and maximum flow. Pumps with high efficiency over a vide speed range are desirable as well as pumps wich speed curves Chat parallel the hea-axis on Che head-versus-flow curves. Pumps wich speed curves chat parallel the flow axis will easily lose suction when speed decreases. Self-priming pumps are slightly less efficient than those that are primed. If a pump operaCes in a locaCion where it can be checked each morning to ensure that ic sCarts pumping when the sun comes up, the higher efficiency pump is recom­mended. If the pump cannot be checked frequently, or if Che available tech­nology does not have the capability of priming the pump, a self-priming pump is recommended. There is always the possibility of a grain of sand or a piece of vegetation getting caught in a foot valve and allowing the 3rime Co be lose overnight or during cloud cover. If a self-priming pump is used, the foot valve and Che resulting friction head loss through it can he delated, possibly compensating for the lower efficiency of the pump.

This effort was conducted solely on low-head pumps. A similar efforc should be undertaken Co find and evaluate deep well pumps necessitating the use of submersible motors. As high-power electronics develop, the use of brushiess dc motors in the 1-hp range should be investigated. Methods of adapting variable speed controls used for ac motors should be investigated for scarting an ac pump motor wich low insolation and maintaining it at maximum speed con­sistent with available insolation throughout the day. Deep well pumps need to be evaluated for different depths when run at variable speeds. Axial flow pumps may be more efficient at intermediate depths of 5 to 30 m than the multistage turbine pumps required for depths over 30 m.

37

Ss?I$

3S

5=*!#

APPENDIX A

MOTOR-SOLAR ARRAY PERFORMANCE REQUIREMENTS

Figure A-l represents the response curves of a solar array that provides power for a dc motor and pump load* The family of solid curves indicates the per­formance at 28°C and varying insolation intensities. The lower intensities represent periods close to sunrise or sunset. The value 100 mW/cm represents nominal noon intensity and 120 mW/cm represents intensities at noon on an exceptionally clear day, such as the day following a snowstorm. Dashed line curves show performance at 0° and 56°C at 100 mW/cm~, 56°C at 120 mW/cm~, and 0° at 25 raW/cm2.

The point on any temperature-intensity curve at which the array operates is a function of the connected load. The optimum place to operate on the 120 mW/ cm.--36°C curve is point A, the maximum power point. Points 3 and C represent the most likely maximum power points for normal operation •• of the array. Point C is the design power at 768 W. The loci of the maximum power points for 0°, 25°, and 56°C are shown crossing the intensity curves.

If a motor that was mechanically coupled to a centrifugal ?<ir*.T> wer* connected directly across the arrays, the desired motor performance, with respect to the array, is shown by the circle dotted line curves.* The sloping line from the origin to R represents the dc resistance of the armature with no rotation. This is arbitrarily shown as 0.33 ohms (4 V and 12 A). As the intensity increases after sunrise, the current through the armature increases to point T where sufficient torque is built up to start rotation. 'Then rotation starts, the back IMF generated in the armature raises the voltage as the speed increases to point P. At this point, sufficient load is imposed on the motor by the pump to stabilize speed*, current, and voltage which will not increase until the solar intensity rises and provides more power. As more power is available, both current and voltage increase until the maximum power available is achieved. For maximum operating efficiency, the motor driving the pump should operate at the maximum power point of the array as much as possible. The motor performance curve should ideally become parallel to and lie between the loci of maximum power points at 56° and 28°C for all Intensities above 43 miT/cm .

*For a more detailed discussion on the performance of motors directly connected to solar arrays, see: J. A. Roger. 1979. "Theory of Direct Coupling 3etween DC Motors and Photovoltaic Solar Arrays." Solar Energy. Vol. 23; pp. 192-198.

ss?i« -TR-U23

16 20 24

Voltage (V)

28 32 36 40

Figure A-l. Response Curves of a Solar Array

i0

5=?i m

APPENDIX B

EQUIPMENT LIST

Equipment

Pyranoraeter

Wind

Pressure

Flow

rpra/Torque

voltage

Current

Oats System

Data Recorder

Thermocouple

3attery

Battery

Motor (30 V)

Pump

Motor (90 V)

Pump

Company

Epply

R. M. Young

Robinson Halpern

Flow Technology

LeBowe

Simpson Type 524

Simpson Type 524 15uA Simpson Shunt 50A 50MV

Accurex

Techtran

Gordon

Gould

C&D

Honeywell

Pacific Punp Co.

Honeywell

Crane-Demming

(PACO)

Model

PSP

Propvane 35403C

152B-P130D-F-V-41

FT-20NK-90LJG0 LFA-303-KLX

1104-500

15114

15092 6709

Auto data 10

317TI

T-24-1-CU504

George Power 24

6QP75-5

BA3637-3254-48B

11-12505-701091

SR532-2212-56BC

1 1/2 8 F6

Serial Number

19381F3

None

4340

2B800 50115

1404

.. 4 MA

NA MA

3-365

4986/4987

NA

MA

MA

None

FSB651S2

None

181

41

•i

42

=?! « S:l«i

APPENDIX C

COMPUTATIONS AND CONVERSIONS

Watts • volts " Amperes

Watts, motor out » Torque • rpm/K

T(ln-lb) • ft . IS1 . 2T I2i 746 W hp-min v ; 12 in min rev hp 33,000 ft-lb

T(in-lb) • r e V min 34.48

' W-rad

Watts = T("-m) - — — * TT;— • 2^ = 7(.I-m) •

Watts, pump out = Pressure • Flow Rate • C

3 P iL_ . I 4 4 l r t " . f t , gal_ . 8.33 l b

. 2 c 2 62.35 l b ' min ' <?al i n f t

hn n i n 746 W

C

33,000 f t - l b hp

? i ^ . . * | i . . 0 .4349 W . 2 mm i n

= 0.4349 ^ _ =£L__!I J. a • g a l

Watts =* P(kPa) • — s

Torque . «* i n - l b • 0 .11298 = N-m rT-m • 8.351 =• in-lb

T;in ^0 s rev min 9.549

9.549 ."7-m/W-rad

43

SBx\ TR-U23

e. Pressure = — T * 6.895 =» kPa in

kPa • 0.145 = - ^ (psi) in

f. Volume = gal • 3.7854 =» L L • 0.2642 - gal

44

APPENDIX D

V

30.0 30.0 30.0 30.0 30.0

30.0 30.0 30.3 31.0

24.0 24.0 24.0 24.0 24.5

Table I>-1.

A

30.5 29.0 28.6 28.0 27.5

27.0 26.2 23.:"! i. 'i . -J

22.3 21.3 20.0 13.0 14.0

Motor Input (Watts;

915.0 870.0 858.0 840.0 325.0

310.0 736.0 696.9 339.)

535.2 511.2 430.0 432.0 343.0

Data on (Labora

) (N-m;

2.7 2.6 2.6 2.5 2.5

2.4 2.4 2.0 i .7

2.0 1.9 1.7 1.6 1.2

L PACO Pump tory Tests)

Torque

) (in-lb)

24 23 23 22 22

21 21 13 i_5

13 L i

15 ^ -•

i_i

with 30-7 Motor

Speed (rpm)

2410 2430 2440 2450 2470

2480 2500 2570 2680

1930 2000 2030 2090 2170

Motor OutDUt (Watts)

678.8 656.0 663.9 634.0 641.6

616.2 619.0 544. 5 458.0 Avg.

432.7 402.0 360.4 346.3 232.5 Avg.

Motor Efficiency

(%)

74.2 75.4 77.4 75.4 77.8

76.1 73.7 ,73.0 77.8 76.8

30.3 73.6 75.0 30.2 32.4 79.2

Test at 30 V

Test' at 24 V

Motor Output (Watts)

673.8 656.0 603.9 634.0 641.6

616.2 619.0 544.5 458.0 Avg.

432.7 402.0 360.4 346.3 282.5 Avg.

Motor Efficiency

(%)

74.2 75.4 77.4 75.4 77.8

76.1 78.1 78.0 77.8 76.8

80.8 78.6 75.0 80.2 82.4 79.2

Pressure

0<Pa)

101.4 115.3 122.7 124.1 131.0

134.4 141.3 158.6 168.9

74.5 82.7 93.1 103.4 0.0

(psi)

14.7 16.8 17.8 18.0 19.0

19.5 20.5 23.0 24.5

10.8 12.0 13.5 15.0 16.5

Flow

(L/s)

166.2 142.7 133.6 119.2 115.1

104.5 96.5 55.6 0.0

135.1 108.6 85.6 53.0 0.0

Rate

(gpm)

43.9 37.7 35.3 31.5 30.4

27.6 25.5 14.7 0.0

35.7 23.7 22.6 14.0 0.0

PUED Outout (Watts)

301.3 295.9 293.6 264.9 269.3

251.5 244.3 158.2

180.0 160.9 142.6 93.1

Pump Efficiency

CO

44.4 45.1 44.2 41.8 42.0

40.8 39.5 29.1

41.6 40.0 39.6 28.3

System Efficiency

CO

32.9 34.0 34.2 31.5 32.7

31.0 31.1 22.7

33.7 31.5 29.7 22.7

45

S=?l«

46

S = 3 1 * TR-1423

APPENDIX E

Table E-l. Data on Crane-Deming Pump with 90-V Motor (Laboratory Tests)

Voltage (V)

50

60

70

80

90

100

110

120

Current (A)

3.3

4.0

5.0

6.0

7.5

8.5

10.0

11.0

Power (W)

165

240

350

480

675

850

1100

1320

Speed (rpm)

920

1080

1250

1440

1620

1770

1960

2120

Torqi

(N-m) (1

1.1

1.5

1.8

2.3

2.8

3.3

3.7

4.4

.n-lt

10

13

16

20

25

29

33

39

Pressure

>)(kPa)

20.7

31.0

41.4

55.2

72.4

91.0

113.1

134.4

(psi)

3.0

4.5

6.0

8.0

10.5

13.2

16.4

19.5

Flow

(L/s)

66.2

90.5

111.7

130.6

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164.7

181.3

193.0

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(gpra)

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23.9

29.5

34.5

41.5

43.5

47.9

51.0

47

s=?t m TR-U23

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43

?! TR-1423

APPENDIX F

Table F- l . Performance Summary for PACO Pump System (Solar Tests; Data Taken on 1 September 1980)

Time

8:45 9:00 9:15 9:30 9:45 10:00 10:15 10:30 10:45 11:00 11:15 11:30 11:45 12:00 12:15 12:30 12:45 13:00 13:15 13:30 13:45 14:00 14:15 14:30 14:45 15:00 15:15 15:30 15:45 16:00 16:15 16:30 16:45 17:00 17:15 17:30 17:45 18:00

I n s o l a t i o n (kWh/m2)

0 .003 0 .101 0 .214 0 .343 0 .49 0.649 0 .321 1.005 1.203 1.411 1.63 1.359 2 .098 2 .341 2 .59 2.842 3 .009 3.355 3.612 3.868 4 .126 4 .378 4 .625 4.866 5.102 5.328 5.542 5.743 5.93 6.104 6.267 6.413 6.556 6.679 6.766 6.82 6.858 6.886

Motor (kWh)

0 .0 0 .03 0.074 0 .13 0 .198 0.277 0.364 0.461 0.57 0.687 0 .81 0 .941 1.073 1.217 1.361 1.504 1.649 1.793 1.935 2.076 2.217 2.353 2.487 2.616 2 .74 2.858 2.969 3.072 3.164 3.245 3.315 3.374 3.43 3.473 3.495 3.498 3.5 3.501

Volume Pumped

(L)

12 .9 506.6

1418.5 2513.5 3775 .3 5199.5 6732.6 8303.2

10002.9 11739.5 13530.7 15365.7 17282.7 19182.2 21127.3 23048.3 24973.9 26900.5 23815.1 30721.3 32643.5 34544.0 36442.2 38306.0 40128.6 41922.5 43659.3 45312.0 46860.2 48348.3 49694.7 50874.3 52037.1 53002.4 53553.6 53832.2 54098.3 54342.1

Pump (kWh)

0 .0 0 .001 0 .004 0 .011 0 .019 0.032 ^ .048 0.065 0.086 •0.11 0 .135 0 .153 0 .192 0.222 0 .254 0 .285 0 .316 0.347 0 .378 0 .408 0 .439 0 .468 0 .498 0.525 0 .551 0 .575 0 .597 0.617 0 .633 0.646 0 .657 0.664 0 .671 0 .674 0 .675 0 .674 0 .674 0.674

49

3=;i m TR-1423

Table F-2. Average Data for PACO Pump System

(Data Taken on 1 September 1981)

Time

8:45 9:00 9:15 9:30 9:45 10:00 10:15 10:30 10:45 11:00 11:15 11:30 11:45 12:00 12:15 12:30 12:45 13:00 13:15 13:30 13:45 14:00 14:15 14:30 14:45 15:00 15:15 15:30 15:45 16:00 16:15 16:30 16:45 17:00 17:15 17:30 17:45 18:00

Insolation (W/m2)

351.5 415.87 475.28 539.65 599.08 653.52 703.05 747.62 302.05 341.64 886.22 925.83 950.56 975.34 995.12 1005.04 1010.01 1014.96 1024.85 1000.11 1005.1 985.24 970.39 950.62 915.96 376.32 821.89 777.33 722.87 673.36 648.61 623.83 455.52 470.36 198.05 203.01 103.97 108.93

SAl* Current

(A)

8.402 9.771 11.225 12.704 14.063 15.276 16.261 17.235 18.334 19.147 19.912 20.621 21.136 21.566 21.87 21.965 22.011 22.141 21.805 21.931 21.672 21.321 21.006 20.373 19.898 19.243 18.439 17.5 16.406 15.017 14.133 13.548 9.967 10.121 4.406 4.257 2.278 2.278

SAl Voltage

(V)

3.322 15.598 17.634 19.258 20.457 21.456 22.243 23.505 24.141 24.765 25.177 25.59 25.714 25.814 26.026 25.739 25.702 25.515 25.49 25.49 25.304 24.903 24.803 24.342 23.992 23.566 22.98 22.206 21.207 20.17 19.421 18.833 15.462 15.374 2.086 2.648 1.886 1.398

Pump (V)

2.523 14.649 16.535 17.996 19.096 19.932 20.657 21.769 22.38 22.941 23.229 23.529 23.703 23.741 23.878 23.616 23.592 23.379 23.354 23.342 23.218 22.342 22.703 22.331 22.081 21.73 21.194 20.457 19.558 18.721 18.022 17.51 14.513 14.388 1.661 2.236 1.649 1.649

Pressure (kPa)

-1.2 9.4 15.2 22.6 29.2 34.5 38.1 42.2 46.1 i 49.8 " 52.6 55.5 56.5 57.6 58.3 57.9 53.6 56.5 57.5 58.2 57.1 55.6 54,3 52.7 50.0 47.5 44.7 41.0 35.2 31.1 25.9 22.3 11.9 11.2

-11.8 -4.8 -2.8 -2.1

Flow Rate (L/s)

0.4 0.8 1.1 1.2 1.4 1.6 1.7 1.8 1.8 2.0 2.0 2.1 2.1 2.1 O 1

2.1 2.1 2.0 2.1 2.1 2.1 2.1 2.0 2.0 2.0 1.9 1.9 1.7 1.7 1.6 1.5 1.4 1.1 0.9 0.3 0.2 0.3 0.2

*SA1 is Solar Array #1 from Solenergy.

50

5 = S i * TR-1423

APPENDIX G

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5=*! $ TR-1423

APPENDIX H

PROCEDURE FOR DESIGN OP A WATER PUMPING SYSTEM

The design of a water pumping system is accomplished as follows:

Given: Available funds, head to which water must be pumped, insolation and temperatures for the area, and knowledge that water is avail­able.

Procedure:

1. Allocate 30% of funds to solar array. (As array costs decrease, this allocation can decrease.)

2. Determine array size in peak watts and watt hours/day that can be pro­cured. Installed costs of the array must be determined, for the time period and location desired. In 1981 installed costs in the United States were of the order of $16 per peak watt.

3. Using 75% efficiency for a typical motor and 95% efficiency for elec­trical connections, determine power available for pumping.

•i. Enter pump curves with horsepower and head, and find pump that will provide maximum flow rate at maximum efficiency.

5. Determine piping requirements and compute friction head for this flow rate.

6. Go back to pump curve and determine new operating point using basic head plus friction head and available horsepower. Iterate steps 4,5, and 6 until a maximum flow rate can be determined.

7. Find a dc motor that will match the power and speed requirement defined by the pump curve. In general, off-the-shelf motors should be selected using the highest standard voltage up to 220 V for domestic systems; higher voltage can be considered for commercial systems.

3. 'Then the motor most closely meeting the requirements is found, go back to step 3 and see if anything has changed. If necessary, update.

9. Design array so that the pump-loaded motor operating point in amperes and volts (I and V) corresponds to the maximum power point on the I-V curve of the array as defined by the expected insolation and average maximum array temperatures. Solar arrays can be formed by series parallel connection of panels. Care must be taken to match the cur­rent of all series-connected panels as closely as possible or the estimate of 95% connecting efficiency used in step 3 will be exceeded.

10. Now add exact costs of array, pump, motor, wiring, pipe, and installa­tion. If the costs are within budget all is well, if not go back to step 1 and iterate again.

53

D o c u m e n t Con t ro l Page

1. Seal Report No.

SERI/TR-214-H23 2. NTIS Accession No.

<*. Title and Subtitle

Evaluation of Pumps and Motors for PV Water Pumping Systems

7. Autnor(s) David Waddington and Ann Herlevich

9. Performing Organization Name ana Adaress

Solar Energy Research Ins t i tu te 1617 Cole Boulevard Golden, Colorado 80401

12. Sponsoring Organization Name ana Address

3. Recioient's Accession No.

5. P'joiication Date

June 1982 6.

3. Performing Organization Hept. No.

10. Proiect/TasK/WorK Unit No.

1091.50 11. Contract (C) or Grant (G) No.

(C)

(G)

13. Tyoe of Report 4 Penoo Covered

Technical Report 14.

15. Suooismentary Notes ;

'•*. -^cstrac; :Limit: 2C0 worasi

Two e lec t r i c , motor-driven water pumps were tested in conjunction with a photo­vol ta ic (PV) array that provided the e lec t r ica l energy to run the pumps. The purpose of the tests was to evaluate the performance of currently available,low-cost pumping systems powered by PV arrays. The performance and cost of these systems were compared with analogous data from s imi lar , higher priced pumps and motors currently used with many PV water pumping systems. The two pump systems considered reoresent production equipment available from U.S. industry and cost less than 50" of equivalent pumps ins ta l led with PV pumping systems in the U.S. and in developing countries. Flow rates, pumping heads, and ef f ic iency were com­parable in both test pumps and equivalent pumps. Motor performance, when the motor was d i rec t l y connected to the PV array and loaded with the pump, was examined. The conclusion drawn from th is experiment is that commercially ava i l ­able, low-cost water pump systems w i l l perform sa t i s fac to r i l y when powered by PV arrays.

17. Gocument Analysis a. Oescnotor f lec t r ic moto rs ; Per formance t e s t i n g : P h o t o v o l t a i c power s u p o l i e s ; Per fo rmance t e s t i n g

b. identifiers/Open-ended Terms S o l a r E n e r g y R e s e a r c h I n s t i t u t e T e s t F a c i l i t y ; l o w

h e a d pumps

o. UC Categories

53D

18. Availaoility Statement National Technical Information Service U.S. Department of Commerce 5285 Port Royal Road SDnnaf ie ld , Vi ra in ia 22161

19. No. ot Pages

66 20. ?r.ce

$5.25 Form No. 0069 (3-25-32)